Monitoring the Large Proper Motions of Radio Sources in the Orion BN/KL Region

Abstract

We present absolute astrometry of four radio sources in the Becklin-Neugebauer/Kleinman-Low (BN/KL) region, derived from archival data (taken in 1991, 1995, and 2000) as well as from new observations (taken in 2006). All data consist of 3.6 cm continuum emission and were taken with the Very Large Array in its highest angular resolution A configuration. We confirm the large proper motions of the BN object, the radio source I (GMR I) and the radio counterpart of the infrared source n (Orion-n), with values from 15 to 26 km/s. The three sources are receding from a point between them from where they seem to have been ejected about 500 years ago, probably via the disintegration of a multiple stellar system. We present simulations of very compact stellar groups that provide a plausible dynamical scenario for the observations. The radio source Orion-n appeared as a double in the first three epochs, but as single in 2006. We discuss this morphological change. The fourth source in the region, GMR D, shows no statistically significant proper motions. We also present new, accurate relative astrometry between BN and radio source I that restrict possible dynamical scenarios for the region. During the 2006 observations, the radio source GMR A, located about 1' to the NW of the BN/KL region, exhibited an increase in its flux density of a factor of ~3.5 over a timescale of one hour. This rapid variability at cm wavelengths is similar to that previously found during a flare at millimeter wavelengths that took place in 2003.

Accepted for publication in ApJ

References in corpus (8)

• The distance to the Orion Nebula
• A Parallactic Distance of 389 +24/-21 parsecs to the Orion Nebula Cluster from Very Long Baseline Array Observations
• Astrometric accuracy of phase-referenced observations with the VLBA and EVN
• Dust and gas emission in the prototypical hot core G29.96-0.02 at sub-arcsecond resolution
• Imaging the Ionized Disk of the High-Mass Protostar Orion-I
• A 1.3 cm wavelength radio flare from a deeply embedded source in the Orion BN/KL region
• OH maser disc and outflow in the Orion-BN/KL region
• New Radio Sources and the Composite Structure of Component B in the Very Young Protostellar System IRAS 16293-2422

Cited by in corpus (37)

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• ALMA observations and modeling of the rotating outflow in Orion Source I
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• From downtown to the outskirts: a radio survey of the Orion Nebula Cluster
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• An orbital release model for the Orion BN/KL fingers
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• Astrometry of the Dynamical Ejection of the Becklin-Neugebauer Object from theta^1 Ori C
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